Now that the goal of universal primary education has been achieved in Ghana, the nation's aim is to expand higher education as a key to development. We argue that this expansion will necessitate the gradual addition of Ghanaian languages as a medium of instruction. We innovatively explain why this is so by comparing the achievements of the Ghanaian education system with one of the best education systems in the world. We use the conceptual distinction between 'discerned' and 'designed' languages to discuss the problem of which languages to choose. We propose five scientific principles that could guide the introduction of Ghanaian languages and suggest concrete steps that could be taken over the coming years to make the transition practically possible. As such, we present a way of looking at using indigenous languages as a medium of instruction that has relevance for other African countries as well.